Roth IRAs are the way to go (if you qualify)

IRAs are a great way to save, if you qualify. CNBC personal finance correspondent Sharon Epperson answers viewers' questions about IRA benefits, restrictions and options.

I've received a lot questions on Twitter about Roth IRAs and saving for retirement.

One viewer—E. H.—tweeted: "I have a Roth IRA but my income is above the limit. Should I start a regular IRA and roll it into a Roth at year end?"

Roth IRAs are a terrific way to save and invest for retirement. You make after-tax contributions and earnings grow tax-free. Unlike regular IRAs, withdrawals from a Roth account are tax-free in retirement, as long as you meet certain requirements.

You can contribute up to $5,500 in a regular or Roth IRA this year, or $6,500 if you're 50 or older. But not everyone can contribute to a Roth IRA. Individuals making over $129,000 this year and married couples who make over $191,000 and file taxes jointly are ineligible.

Income limits on deductible IRAs are even lower. Yet anyone can make a nondeductible IRA contribution. If you do that, you can then convert the money to a Roth IRA. If you do the conversion immediately, the money that you convert from the nondeductible IRA to the Roth should be tax free, since you've already put in after-tax dollars.

But there's an important caveat: Retirement expert Denise Appleby warns that when you convert a non-deductible amount from a regular IRA to a Roth, the IRS looks at all of your regular IRA accounts.

The IRS treats all of those balances as one regular IRA. So if you have other regular IRA accounts, the amount that you convert will include a pro-rated amount of pre-tax and after tax balance—your non-deductible contribution will no longer be converted completely tax-free.